Hi Jens, The 1st patch runs idle hctx after dealy in scsi_mq_get_budget(), so that we can keep same behaviour with before, and it can be thought as a fix. The 2nd patch cleans up RESTART, and removes handling for TAG_SHARED from current blk-mq's RESTART mechanism because SCSI_MQ can covers its restart by itself, so that no need to handle TAG_SHARED in blk-mq RESTART. And >20% IOPS boost is observed in my rand read test over scsi_debug. John, please test this two patches and see if it may improve your SAS IO performance, and you can find the two patches in the following branch: https://github.com/ming1/linux/commits/blk_mq_improve_restart_V1 Ming Lei (2): SCSI: run idle hctx after delay in scsi_mq_get_budget() blk-mq: don't handle TAG_SHARED in restart block/blk-mq-sched.c | 78 +++---------------------------------------------- drivers/scsi/scsi_lib.c | 13 +++++++-- 2 files changed, 14 insertions(+), 77 deletions(-) -- 2.9.5
